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Redirecting underseat AC blowers

Discussion in 'Gen 4 Prius Main Forum' started by Jeff Gold, Sep 29, 2019.

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  1. Jeff Gold

    Jeff Gold Junior Member

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    We've used a Toyota Prius since the first generation as our car of choice for safely transporting rescue animals for our dog rescue charity.

    This week we pickup our 2019 Prius Limited which will replace a 2012 Prius. We will keep the back seats permanently down, the back area is for rescue dogs, the front two seats for people.

    I've noticed with the seats down -- especially since we have a lot of items stored behind the two front seats -- little or no AC creeps up from the floor vents... so I had an idea to try this time...

    We would like to attach some sort of custom "mini-duct" to redirect AC air blowing from underneath the seats into a duct tube of some sort which would then come up in the center to the level just above the seats when they are folded down, so it would then blow to the back of the car above the folded seats, instead of just at the floor.

    Before I dive into experimenting, has anyone else ever tried this? Or have any suggestions before we try?

    Thanks!
     
    #1 Jeff Gold, Sep 29, 2019
  2. alanclarkeau

    alanclarkeau Senior Member

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    I'd test how the airflow is from them - that it's COLD - my last car which had rear floor vents (VOLVO) only sent heated air through them, but PRIUS might be different. Check it first.
     
    #2 alanclarkeau, Sep 29, 2019
  3. Jeff Gold

    Jeff Gold Junior Member

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    Great point. When I felt them at dealer they didn't seem to be putting out much cool air, but there was some flow. But maybe like you said they generally are more for heat? In which case we can just continue what we already do which is to rely on the front air vents blowing to the back and if really hot, we have a lighter-socket powered fan that sits in the middle helping the cool air get to the very back.

    Anyone else have experience with this?
     
    #3 Jeff Gold, Sep 29, 2019
  4. alanclarkeau

    alanclarkeau Senior Member

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    When I've got the grandchildren in the car (no not in the cargo area :eek:), they're comfortable. But I always direct my centre vents straight back and the two outer vents for the front passengers - I find that gives a better overall comfort level as the whole car cools more evenly rather than just air on my face.

    You'll want to turn ECO Climate Mode OFF - as it only sends air to the driver if there are no other passengers. Plus reduces air-cooling.

    NOTE - this is 2016, but I've got no reason to believe that it's changed for 2019. Come to think about it - I'm sure I've had cold air to my feet somehow, so it must be possible to fiddle with buttons and get cold to the back seats.

    upload_2019-9-30_11-43-57.png

    upload_2019-9-30_11-44-31.png upload_2019-9-30_11-44-51.png upload_2019-9-30_11-46-55.png

    upload_2019-9-30_11-48-34.png

    BUT - if you've got ECO on, and no passenger, this is what you get:
    upload_2019-9-30_11-49-36.png
     
    #4 alanclarkeau, Sep 29, 2019
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  5. Jeff Gold

    Jeff Gold Junior Member

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    I've been doing the same with my 2012 Prius. Directing the middle vents straight back. I actually close the two side vents to give the middle vents more "force" to send the air back. The 2019 Limited though, which we bought, has smaller vents to the side of the large screen so it won't be quite as good at sending that center vent air to the back, so checking out these other options. Thanks for the helpful diagrams for airflow, pretty sure this is nearly the same for the rear air vents in the 2019 we bought.
     
    #5 Jeff Gold, Sep 30, 2019
  6. kithmo

    kithmo Couch Potato

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    I would be careful about re-directing air flow from those lower vents, they help keep the HV battery cool. On a hot day you may have trouble with the HV battery overheating if there is not enough air going in to the vent on the lower part of the back seat. :cautious:
     
    #6 kithmo, Sep 30, 2019
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  7. alanclarkeau

    alanclarkeau Senior Member

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    I don't think it'd cause a problem - they don't usually have any air-flow, and only generally if the car is being heated - 99.5% of my driving is alone, and nothing comes out of those vents unless I flick off ECO mode.
     
    #7 alanclarkeau, Sep 30, 2019
  8. hill

    hill High Fiber Member

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    Extra important to heed that advice - because the pack is only air-cooled. So the hotter it gets, the more important a sufficient volume crossing the battery's path becomes.
    .
     
    #8 hill, Sep 30, 2019
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  9. Dr.Love

    Dr.Love New Member

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    Did you ever try this? I’m thinking of doing this on my 2010.
     
    #9 Dr.Love, Jun 20, 2021
  10. FuelMiser

    FuelMiser Senior Member

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    You will definitely want to pay attention to the Front/Rear Bias switch on the HVAC, new in Gen 4. When the light is lit, the car reduces air flow from the dash vents, thinking the passengers are only in the front seats. In fact, it will even reduce air flow to the front passenger side when there is no weight in the front passenger seat. So to get max airflow from the front dash vents, you need to manually select this switch off. Also, don't select HVAC ECO mode, or use the ECO drive mode which puts the HVAC in ECO mode by default.
     
    #10 FuelMiser, Jun 21, 2021
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  11. ChapmanF

    ChapmanF Senior Member

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    I can't help noticing that in the ductwork schematic as posted by alanclarkeau in #4, the rear outlets *18 and *19 are on a simple common duct with the front footwell outlets *13 and *14, with no mechanism capable of selectively blocking them off:

    [​IMG]

    And then the mode chart seems to show that the rear outlets are used together with the front footwell outlets normally, but not in ECO mode. I wonder if that's a typo or, hmm, aspirational statement, given that there isn't any mechanism there to create that difference.

    I guess ECO mode might limit the top blower speeds selected in Auto mode (I think it does that in my Gen 3), and as the rear outlets are farther away and those ducts are pretty skinny, they might be saying you just don't get much air there at the ECO-limited blower speeds.

    I wonder whether any newer models than the 2016 (where alanclarkeau got the diagram) have really added separate damper control for the rear ducts.
     
    #11 ChapmanF, Jun 21, 2021
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